diff --git a/.bazelrc b/.bazelrc
index 30229f7da7c..1c1d285ac5f 100644
--- a/.bazelrc
+++ b/.bazelrc
@@ -34,7 +34,7 @@ build --enable_platform_specific_config
 # Options for Linux.
 ###############################################################################
 
-build:linux --cxxopt=-std=c++17 --host_cxxopt=-std=c++17
+build:linux --cxxopt=-std=c++20 --host_cxxopt=-std=c++20
 build:linux --cxxopt=-Wno-sign-compare --host_cxxopt=-Wno-sign-compare
 build:linux --cxxopt=-Wno-range-loop-construct --host_cxxopt=-Wno-range-loop-construct
 
@@ -45,7 +45,7 @@ build:linux --cxxopt=-Wno-range-loop-construct --host_cxxopt=-Wno-range-loop-con
 # Sets the default Apple platform to macOS.
 build --apple_platform_type=macos
 build:macos --features=-supports_dynamic_linker
-build:macos --cxxopt=-std=c++17 --host_cxxopt=-std=c++17
+build:macos --cxxopt=-std=c++20 --host_cxxopt=-std=c++20
 build:macos --cxxopt=-Wno-sign-compare --host_cxxopt=-Wno-sign-compare
 build:macos --cxxopt=-Wno-dangling-field --host_cxxopt=-Wno-dangling-field
 build:macos --cxxopt=-Wno-range-loop-construct --host_cxxopt=-Wno-range-loop-construct
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1e29e4a3736..2637e1a0b84 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -28,11 +28,7 @@ message(STATUS "${PROJECT_NAME} version: ${PROJECT_VERSION} release: ${RELEASE}"
 #message(STATUS "minor: ${PROJECT_VERSION_MINOR}")
 #message(STATUS "patch: ${PROJECT_VERSION_PATCH}")
 
-if(MSVC)
-  set(CMAKE_CXX_STANDARD 20)
-else()
-  set(CMAKE_CXX_STANDARD 17)
-endif()
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
diff --git a/bazel/README.md b/bazel/README.md
index 61e3a212c65..4ddd69d6df8 100644
--- a/bazel/README.md
+++ b/bazel/README.md
@@ -72,35 +72,15 @@ OR-Tools depends on several mandatory libraries.
 
 ## Compilation
 
-You must compile OR-Tools using at least C++17 (C++20 on windows):
-
-*   on UNIX:
-
-    ```sh
-    bazel build -c opt --cxxopt=-std=c++17 ...
-    ```
-
-*   on Windows when using MSVC:
-
-    ```sh
-    bazel build -c opt --cxxopt="/std:c++20" ...
-    ```
+```sh
+bazel build -c opt //ortools/... //examples/...
+```
 
 ## Testing
 
-You may run tests using:
-
-*   on UNIX:
-
-    ```sh
-    bazel test -c opt --cxxopt=-std=c++17 ...
-    ```
-
-*   on Windows when using MSVC:
-
-    ```sh
-    bazel test -c opt --cxxopt="/std:c++20" ...
-    ```
+```sh
+bazel test -c opt //ortools/... //examples/...
+```
 
 ## Integration
 
diff --git a/cmake/dependencies/CMakeLists.txt b/cmake/dependencies/CMakeLists.txt
index 432f7f53f8a..d164b28e070 100644
--- a/cmake/dependencies/CMakeLists.txt
+++ b/cmake/dependencies/CMakeLists.txt
@@ -424,7 +424,8 @@ endif()
 # ##############################################################################
 # Coinutils
 # ##############################################################################
-# Coin-OR does not support C++17/C++20 (use of 'register' storage class specifier)
+
+# Coin-OR uses the 'register' storage class specifier which requires C++11.
 set(CMAKE_CXX_STANDARD 11)
 if(WIN32)
   set(BUILD_SHARED_LIBS OFF)
@@ -532,14 +533,12 @@ if(BUILD_Cbc)
   message(CHECK_PASS "fetched")
 endif()
 
+# End of Coin-OR dependencies, setting the properties back to their previous
+# values.
+set(CMAKE_CXX_STANDARD 20)
 if(WIN32)
   set(BUILD_SHARED_LIBS ON)
 endif()
-if(MSVC)
-  set(CMAKE_CXX_STANDARD 20)
-else()
-  set(CMAKE_CXX_STANDARD 17)
-endif()
 
 ###############
 ##  TESTING  ##
diff --git a/ortools/base/BUILD.bazel b/ortools/base/BUILD.bazel
index 1137d5d7557..b6a3e0acd9b 100644
--- a/ortools/base/BUILD.bazel
+++ b/ortools/base/BUILD.bazel
@@ -34,12 +34,6 @@ cc_library(
     ],
 )
 
-cc_library(
-    name = "array",
-    hdrs = ["array.h"],
-    deps = ["@abseil-cpp//absl/utility"],
-)
-
 cc_library(
     name = "base",
     srcs = ["version.cc"],
diff --git a/ortools/base/array.h b/ortools/base/array.h
deleted file mode 100644
index a3794886ae3..00000000000
--- a/ortools/base/array.h
+++ /dev/null
@@ -1,56 +0,0 @@
-// Copyright 2010-2025 Google LLC
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-#ifndef ORTOOLS_BASE_ARRAY_H_
-#define ORTOOLS_BASE_ARRAY_H_
-
-//! @todo(corentinl) std::to_array available in C++20.
-
-#include <array>
-#include <cstddef>
-#include <type_traits>
-
-#include "absl/utility/utility.h"
-
-namespace gtl {
-
-namespace internal_array {
-
-template <typename T, std::size_t N, std::size_t... Idx>
-constexpr std::array<std::remove_cv_t<T>, N> to_array_internal(
-    T (&ts)[N], absl::index_sequence<Idx...>) {
-  return {{ts[Idx]...}};
-}
-
-template <typename T, std::size_t N, std::size_t... Idx>
-constexpr std::array<std::remove_cv_t<T>, N> to_array_internal(
-    T (&&ts)[N], absl::index_sequence<Idx...>) {
-  return {{std::move(ts[Idx])...}};
-}
-
-}  // namespace internal_array
-
-template <typename T, std::size_t N>
-constexpr std::array<std::remove_cv_t<T>, N> to_array(T (&ts)[N]) {
-  return internal_array::to_array_internal(ts, absl::make_index_sequence<N>{});
-}
-
-template <typename T, std::size_t N>
-constexpr std::array<std::remove_cv_t<T>, N> to_array(T (&&ts)[N]) {
-  return internal_array::to_array_internal(std::move(ts),
-                                           absl::make_index_sequence<N>{});
-}
-
-}  // namespace gtl
-
-#endif  // ORTOOLS_BASE_ARRAY_H_
diff --git a/ortools/base/filesystem.cc b/ortools/base/filesystem.cc
index a45dc9c1130..94dcfc89d0b 100644
--- a/ortools/base/filesystem.cc
+++ b/ortools/base/filesystem.cc
@@ -15,7 +15,7 @@
 
 #include <algorithm>
 #include <exception>   // IWYU pragma: keep
-#include <filesystem>  // NOLINT(build/c++17)
+#include <filesystem>  // NOLINT
 #include <regex>       // NOLINT
 #include <string>
 #include <string_view>
diff --git a/ortools/cpp/CMakeLists.txt.in b/ortools/cpp/CMakeLists.txt.in
index d96b8e24f80..3218fdfee2a 100644
--- a/ortools/cpp/CMakeLists.txt.in
+++ b/ortools/cpp/CMakeLists.txt.in
@@ -9,11 +9,7 @@ message(STATUS "${PROJECT_NAME} version: ${PROJECT_VERSION}")
 #message(STATUS "minor: ${PROJECT_VERSION_MINOR}")
 #message(STATUS "patch: ${PROJECT_VERSION_PATCH}")
 
-if(MSVC)
-  set(CMAKE_CXX_STANDARD 20)
-else()
-  set(CMAKE_CXX_STANDARD 17)
-endif()
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 set(CMAKE_CXX_EXTENSIONS OFF)
 set(CMAKE_INSTALL_RPATH_USE_LINK_PATH True)
diff --git a/ortools/math_opt/elemental/BUILD.bazel b/ortools/math_opt/elemental/BUILD.bazel
index d0e9163fb67..9781f2b6e33 100644
--- a/ortools/math_opt/elemental/BUILD.bazel
+++ b/ortools/math_opt/elemental/BUILD.bazel
@@ -22,7 +22,6 @@ cc_library(
         ":arrays",
         ":elements",
         ":symmetry",
-        "//ortools/base:array",
         "@abseil-cpp//absl/strings:string_view",
     ],
 )
@@ -323,7 +322,6 @@ cc_test(
     srcs = ["arrays_test.cc"],
     deps = [
         ":arrays",
-        "//ortools/base:array",
         "//ortools/base:gmock_main",
         "@abseil-cpp//absl/status",
         "@abseil-cpp//absl/strings",
@@ -459,7 +457,6 @@ cc_library(
     visibility = ["//ortools/math_opt:__subpackages__"],
     deps = [
         ":tagged_id",
-        "//ortools/base:array",
         "@abseil-cpp//absl/log:check",
         "@abseil-cpp//absl/strings:string_view",
     ],
diff --git a/ortools/math_opt/elemental/arrays.h b/ortools/math_opt/elemental/arrays.h
index 082d7c757f9..b8371d1eb4b 100644
--- a/ortools/math_opt/elemental/arrays.h
+++ b/ortools/math_opt/elemental/arrays.h
@@ -36,7 +36,6 @@ namespace operations_research::math_opt {
 //      ```
 template <int n, typename Fn>
 constexpr decltype(auto) ApplyOnIndexRange(Fn&& fn) {
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   return [&fn]<int... is>(std::integer_sequence<int, is...>) mutable {
     return fn.template operator()<is...>();
   }(std::make_integer_sequence<int, n>());
@@ -55,7 +54,6 @@ constexpr decltype(auto) ApplyOnIndexRange(Fn&& fn) {
 template <int n, typename Fn>
 constexpr decltype(auto) ForEachIndex(Fn&& fn) {
   return ApplyOnIndexRange<n>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&fn]<int... is>() { return (fn.template operator()<is>(), ...); });
 }
 
@@ -63,7 +61,6 @@ constexpr decltype(auto) ForEachIndex(Fn&& fn) {
 // last invocation.
 template <typename Fn, typename Tuple>
 constexpr decltype(auto) ForEach(Fn&& fn, Tuple&& tuple) {
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   return std::apply([&fn]<typename... Ts>(
                         Ts&&... ts) { return (fn(std::forward<Ts>(ts)), ...); },
                     std::forward<Tuple>(tuple));
diff --git a/ortools/math_opt/elemental/arrays_test.cc b/ortools/math_opt/elemental/arrays_test.cc
index 865b28caebb..f261dfcabdf 100644
--- a/ortools/math_opt/elemental/arrays_test.cc
+++ b/ortools/math_opt/elemental/arrays_test.cc
@@ -23,7 +23,6 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "gtest/gtest.h"
-#include "ortools/base/array.h"
 #include "ortools/base/gmock.h"
 
 namespace operations_research::math_opt {
@@ -35,7 +34,6 @@ using ::testing::ElementsAre;
 template <auto a>
 constexpr int Sum() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return (a[i] + ... + 0); });
 }
 
@@ -43,17 +41,14 @@ constexpr int Sum() {
 template <auto a>
 constexpr int SumPlusOne() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return (a[i] + ... + 1); });
 }
 
 #if __cplusplus >= 202002L
-// NOLINTBEGIN(clang-diagnostic-pre-c++20-compat)
 TEST(ApplyOnIndexRangeTest, Sum) {
-  EXPECT_EQ(Sum<gtl::to_array({5, 3, 1})>(), 9);
-  EXPECT_EQ(SumPlusOne<gtl::to_array({5, 3, 1})>(), 10);
+  EXPECT_EQ(Sum<std::to_array({5, 3, 1})>(), 9);
+  EXPECT_EQ(SumPlusOne<std::to_array({5, 3, 1})>(), 10);
 }
-// NOLINTEND(clang-diagnostic-pre-c++20-compat)
 #endif
 
 // Returns the weighted sum of the elements of an array-like object `a`, where
@@ -61,39 +56,32 @@ TEST(ApplyOnIndexRangeTest, Sum) {
 template <auto a>
 constexpr double ScaledSum() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return ((i * a[i]) + ... + 0.0); });
 }
 
 #if __cplusplus >= 202002L
-// NOLINTBEGIN(clang-diagnostic-pre-c++20-compat)
 TEST(ApplyOnIndexRangeTest, ScaledSum) {
-  EXPECT_EQ(ScaledSum<gtl::to_array({5, 3, 1})>(), 5.0);
+  EXPECT_EQ(ScaledSum<std::to_array({5, 3, 1})>(), 5.0);
 }
-// NOLINTEND(clang-diagnostic-pre-c++20-compat)
 #endif
 
 // Returns the number of even elements in an array-like object `a`.
 template <auto a>
 constexpr int CountEven() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return ((a[i] % 2 == 0 ? 1 : 0) + ... + 0); });
 }
 
 #if __cplusplus >= 202002L
-// NOLINTBEGIN(clang-diagnostic-pre-c++20-compat)
 TEST(ApplyOnIndexRangeTest, CountEven) {
-  EXPECT_EQ(CountEven<gtl::to_array({5, 4, 8, 1, 10})>(), 3);
+  EXPECT_EQ(CountEven<std::to_array({5, 4, 8, 1, 10})>(), 3);
 }
-// NOLINTEND(clang-diagnostic-pre-c++20-compat)
 #endif
 
 // Returns array of doubles of the same size as `a`, where each element has been
 // halved.
 template <auto a>
 constexpr std::array<double, std::size(a)> Half() {
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   return ApplyOnIndexRange<std::size(a)>([]<int... i>() {
     return std::array<double, std::size(a)>(
         {(static_cast<double>(a[i]) / 2.0)...});
@@ -101,19 +89,16 @@ constexpr std::array<double, std::size(a)> Half() {
 }
 
 #if __cplusplus >= 202002L
-// NOLINTBEGIN(clang-diagnostic-pre-c++20-compat)
 TEST(ApplyOnIndexRangeTest, Half) {
-  EXPECT_THAT(Half<gtl::to_array({5, 4, 8, 1, 10})>(),
+  EXPECT_THAT(Half<std::to_array({5, 4, 8, 1, 10})>(),
               ElementsAre(2.5, 2.0, 4.0, 0.5, 5.0));
 }
-// NOLINTEND(clang-diagnostic-pre-c++20-compat)
 #endif
 
 // Returns true of all elements of `a` are even.
 template <auto a>
 constexpr int AllEven() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return (((a[i] % 2) == 0) && ...); });
 }
 
@@ -121,23 +106,20 @@ constexpr int AllEven() {
 template <auto a>
 constexpr int AnyEven() {
   return ApplyOnIndexRange<std::size(a)>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int... i>() { return (((a[i] % 2) == 0) || ...); });
 }
 
 #if __cplusplus >= 202002L
-// NOLINTBEGIN(clang-diagnostic-pre-c++20-compat)
 TEST(ApplyOnIndexRangeTest, Even) {
-  EXPECT_FALSE(AllEven<gtl::to_array({5, 4, 8, 1, 10})>());
-  EXPECT_TRUE(AnyEven<gtl::to_array({5, 4, 8, 1, 10})>());
+  EXPECT_FALSE(AllEven<std::to_array({5, 4, 8, 1, 10})>());
+  EXPECT_TRUE(AnyEven<std::to_array({5, 4, 8, 1, 10})>());
 
-  EXPECT_TRUE(AllEven<gtl::to_array({8, 2, 6})>());
-  EXPECT_TRUE(AnyEven<gtl::to_array({8, 2, 6})>());
+  EXPECT_TRUE(AllEven<std::to_array({8, 2, 6})>());
+  EXPECT_TRUE(AnyEven<std::to_array({8, 2, 6})>());
 
-  EXPECT_FALSE(AllEven<gtl::to_array({3, 7, 1})>());
-  EXPECT_FALSE(AnyEven<gtl::to_array({3, 7, 1})>());
+  EXPECT_FALSE(AllEven<std::to_array({3, 7, 1})>());
+  EXPECT_FALSE(AnyEven<std::to_array({3, 7, 1})>());
 }
-// NOLINTEND(clang-diagnostic-pre-c++20-compat)
 #endif
 
 // A example of a more complex reduce operation using `ForEachIndex`. Here, we
@@ -153,7 +135,6 @@ TEST(ForEachIndexTest, CollectTest) {
 
   EXPECT_THAT(
       ForEachIndex<21>(
-          // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
           [&may_fail, failed_indices = std::vector<int>()]<int i>() mutable
               -> const std::vector<int>& {
             if (!may_fail(i).ok()) {
diff --git a/ortools/math_opt/elemental/attr_storage.h b/ortools/math_opt/elemental/attr_storage.h
index f8d255559c5..d3b17655884 100644
--- a/ortools/math_opt/elemental/attr_storage.h
+++ b/ortools/math_opt/elemental/attr_storage.h
@@ -144,7 +144,6 @@ class SlicingSupport {
   using Key = AttrKey<n, Symmetry>;
 
   void AddRowsAndColumns(const Key key) {
-    // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
     ForEachDimension([this, key]<int i>() {
       if (MustInsertNondefault<i>(key, Symmetry{})) {
         key_nondefaults_[i][key[i]].Insert(key.template RemoveElement<i>());
@@ -154,7 +153,6 @@ class SlicingSupport {
 
   // Requires key is currently stored with a non-default value.
   void ClearRowsAndColumns(Key key) {
-    // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
     ForEachDimension([this, key]<int i>() {
       const auto& key_elem = key[i];
       auto& nondefaults = key_nondefaults_[i];
@@ -176,11 +174,9 @@ class SlicingSupport {
   std::vector<Key> Slice(const int64_t key_elem) const {
     return SliceImpl<i>(
         key_elem, Symmetry{},
-        // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
         [key_elem]<int... is>(KeySetExpansion<is>... expansions) {
           std::vector<Key> slice((expansions.key_set.size() + ...));
           Key* out = slice.data();
-          // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
           const auto append = [key_elem, &out]<int j>(
                                   const KeySetExpansion<j>& expansion) {
             expansion.key_set.ForEach(
diff --git a/ortools/math_opt/elemental/attributes.h b/ortools/math_opt/elemental/attributes.h
index 8f76aeacbbc..178573b1e1f 100644
--- a/ortools/math_opt/elemental/attributes.h
+++ b/ortools/math_opt/elemental/attributes.h
@@ -22,7 +22,6 @@
 #include <type_traits>
 
 #include "absl/strings/string_view.h"
-#include "ortools/base/array.h"
 #include "ortools/math_opt/elemental/arrays.h"
 #include "ortools/math_opt/elemental/elements.h"
 #include "ortools/math_opt/elemental/symmetry.h"
@@ -86,7 +85,7 @@ struct BoolAttr0TypeDescriptor
 
   enum class AttrType { kMaximize };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>(
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>(
       {{.name = "maximize", .default_value = false, .key_types = {}}});
 };
 
@@ -100,7 +99,7 @@ struct BoolAttr1TypeDescriptor
     kIndConActivateOnZero,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>(
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>(
       {{.name = "variable_integer",
         .default_value = false,
         .key_types = {ElementType::kVariable}},
@@ -121,7 +120,7 @@ struct IntAttr0TypeDescriptor
     kObjPriority,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "objective_priority", .default_value = 0, .key_types = {}},
   });
 };
@@ -135,7 +134,7 @@ struct IntAttr1TypeDescriptor
     kAuxObjPriority,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "auxiliary_objective_priority",
        .default_value = 0,
        .key_types = {ElementType::kAuxiliaryObjective}},
@@ -149,7 +148,7 @@ struct DoubleAttr0TypeDescriptor
 
   enum class AttrType { kObjOffset };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>(
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>(
       {{.name = "objective_offset", .default_value = 0.0, .key_types = {}}});
 };
 
@@ -171,7 +170,7 @@ struct DoubleAttr1TypeDescriptor
     kIndConUb,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "variable_lower_bound",
        .default_value = -std::numeric_limits<double>::infinity(),
        .key_types = {ElementType::kVariable}},
@@ -217,7 +216,7 @@ struct DoubleAttr2TypeDescriptor
     kIndConLinCoef
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "linear_constraint_coefficient",
        .default_value = 0.0,
        .key_types = {ElementType::kLinearConstraint, ElementType::kVariable}},
@@ -244,7 +243,7 @@ struct SymmetricDoubleAttr2TypeDescriptor
     kObjQuadCoef,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "objective_quadratic_coefficient",
        .default_value = 0.0,
        .key_types = {ElementType::kVariable, ElementType::kVariable}},
@@ -262,7 +261,7 @@ struct SymmetricDoubleAttr3TypeDescriptor
     kQuadConQuadCoef,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "quadratic_constraint_quadratic_coefficient",
        .default_value = 0.0,
        .key_types = {ElementType::kQuadraticConstraint, ElementType::kVariable,
@@ -279,7 +278,7 @@ struct VariableAttr1TypeDescriptor
     kIndConIndicator,
   };
 
-  static constexpr auto kAttrDescriptors = gtl::to_array<AttrDescriptor>({
+  static constexpr auto kAttrDescriptors = std::to_array<AttrDescriptor>({
       {.name = "indicator_constraint_indicator",
        .default_value = VariableId(),
        .key_types = {ElementType::kIndicatorConstraint}},
@@ -312,7 +311,6 @@ using VariableAttr1 = VariableAttr1TypeDescriptor::AttrType;
 template <typename AttrT>
 static constexpr int GetIndexIfAttr() {
   using Tuple = AllAttrTypeDescriptors;
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   return ApplyOnIndexRange<std::tuple_size_v<Tuple>>([]<int... i>() {
     return ((std::is_same_v<std::remove_cv_t<std::remove_reference_t<AttrT>>,
                             typename std::tuple_element_t<i, Tuple>::AttrType>
diff --git a/ortools/math_opt/elemental/attributes_test.cc b/ortools/math_opt/elemental/attributes_test.cc
index 4e82f856dfe..9314b4aefd0 100644
--- a/ortools/math_opt/elemental/attributes_test.cc
+++ b/ortools/math_opt/elemental/attributes_test.cc
@@ -45,7 +45,6 @@ TEST(ToStringTests, EachTypeCanConvert) {
 // with element types.
 TEST(SymmetryTest, AllSymmetricTypesAreCorrect) {
   ForEach(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<typename Descriptor>(const Descriptor&) {
         for (const auto& attr : Descriptor::kAttrDescriptors) {
           Descriptor::Symmetry::CheckElementTypes(attr.key_types);
diff --git a/ortools/math_opt/elemental/derived_data_test.cc b/ortools/math_opt/elemental/derived_data_test.cc
index 5135308303c..af4f96029a6 100644
--- a/ortools/math_opt/elemental/derived_data_test.cc
+++ b/ortools/math_opt/elemental/derived_data_test.cc
@@ -81,7 +81,6 @@ TEST(GetElementTypesTest, Attr2HasElements) {
 
 TEST(AllAttrsTest, Indexing) {
   ForEachIndex<AllAttrs::kNumAttrTypes>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       []<int i>() { EXPECT_EQ((AllAttrs::GetIndex<AllAttrs::Type<i>>()), i); });
 }
 
@@ -140,7 +139,6 @@ TEST(AttrMapTest, Iteration) {
 
   // We should have `NumAttrs()` values `i` per attribute.
   std::vector<int> expected_values;
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   ForEachIndex<AllAttrs::kNumAttrTypes>([&expected_values]<int i>() {
     for (int k = 0; k < AllAttrs::TypeDescriptor<i>::NumAttrs(); ++k) {
       expected_values.push_back(i);
@@ -151,7 +149,6 @@ TEST(AttrMapTest, Iteration) {
 
 TEST(CallForAttrTest, Works) {
   EXPECT_EQ(CallForAttr(DoubleAttr1::kVarUb,
-                        // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
                         []<DoubleAttr1 a>() { return static_cast<int>(a); }),
             static_cast<int>(DoubleAttr1::kVarUb));
 }
diff --git a/ortools/math_opt/elemental/elemental.cc b/ortools/math_opt/elemental/elemental.cc
index 7affab927f5..c72f786cc31 100644
--- a/ortools/math_opt/elemental/elemental.cc
+++ b/ortools/math_opt/elemental/elemental.cc
@@ -38,7 +38,6 @@ namespace operations_research::math_opt {
 Elemental::Elemental(std::string model_name, std::string primary_objective_name)
     : model_name_(std::move(model_name)),
       primary_objective_name_(std::move(primary_objective_name)) {
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   ForEachIndex<AllAttrs::kNumAttrTypes>([this]<int attr_type_index>() {
     using Descriptor = AllAttrs::TypeDescriptor<attr_type_index>;
     for (const auto a : Descriptor::Enumerate()) {
@@ -90,15 +89,12 @@ bool Elemental::DeleteElementUntyped(const ElementType e, int64_t id) {
   for (auto& [unused, diff] : diffs_->UpdateAndGetAll()) {
     diff->DeleteElement(e, id);
   }
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   AllAttrs::ForEachAttr([this, e, id]<typename AttrType>(AttrType a) {
-    ForEachIndex<GetAttrKeySize<AttrType>()>(
-        // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
-        [&]<int i>() {
-          if (GetElementTypes(a)[i] == e) {
-            UpdateAttrOnElementDeleted<AttrType, i>(a, id);
-          }
-        });
+    ForEachIndex<GetAttrKeySize<AttrType>()>([&]<int i>() {
+      if (GetElementTypes(a)[i] == e) {
+        UpdateAttrOnElementDeleted<AttrType, i>(a, id);
+      }
+    });
     // If `a` is element-valued, we need to remove all keys that refer to the
     // deleted element.
     if constexpr (is_element_id_v<ValueTypeFor<AttrType>>) {
diff --git a/ortools/math_opt/elemental/elemental_differencer.cc b/ortools/math_opt/elemental/elemental_differencer.cc
index 6b6bb4b4c1c..2081e360589 100644
--- a/ortools/math_opt/elemental/elemental_differencer.cc
+++ b/ortools/math_opt/elemental/elemental_differencer.cc
@@ -103,7 +103,6 @@ ElementalDifference ElementalDifference::Create(
     }
   }
   AllAttrs::ForEachAttr(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&result, &first, &second]<typename AttrType>(AttrType attr) {
         using Key = typename AttributeDifference<AttrType>::Key;
         AttributeDifference<AttrType>& attr_difference =
@@ -217,7 +216,6 @@ std::string ElementalDifference::Describe(
     }
   }
   AllAttrs::ForEachAttr(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&lines, &difference, &first, &second]<typename AttrType>(AttrType attr) {
         const auto& attr_diff = difference.attr_difference(attr);
         auto attr_value_str = [attr](const Elemental& elemental,
diff --git a/ortools/math_opt/elemental/elemental_export_model.cc b/ortools/math_opt/elemental/elemental_export_model.cc
index bed35273132..aee870d5f57 100644
--- a/ortools/math_opt/elemental/elemental_export_model.cc
+++ b/ortools/math_opt/elemental/elemental_export_model.cc
@@ -64,7 +64,6 @@ absl::Status CanExportToProto(int64_t num_entries) {
 template <int n, typename Fn>
 absl::Status ForEachIndexUntilError(Fn&& fn) {
   absl::Status result = absl::OkStatus();
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   ForEachIndex<n>([&result, &fn]<int i>() {
     if (!result.ok()) {
       return;
@@ -101,7 +100,6 @@ absl::Status ForEachAttrUntilError(Fn&& fn) {
 // in `model`.
 absl::Status ValidateElementsFitInProto(const Elemental& model) {
   return ForEachIndexUntilError<kNumElements>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&model]<int e>() -> absl::Status {
         constexpr auto element_type = static_cast<ElementType>(e);
         RETURN_IF_ERROR(CanExportToProto(model.NumElements(element_type)))
@@ -540,7 +538,6 @@ absl::Status ValidateElementUpdatesFitInProto(
     const Diff& diff,
     const std::array<std::vector<int64_t>, kNumElements>& new_elements) {
   return ForEachIndexUntilError<kNumElements>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&diff, &new_elements]<int e>() -> absl::Status {
         constexpr auto element_type = static_cast<ElementType>(e);
         RETURN_IF_ERROR(
diff --git a/ortools/math_opt/elemental/elemental_to_string.cc b/ortools/math_opt/elemental/elemental_to_string.cc
index d3cc499bd5d..6bbc58b09a1 100644
--- a/ortools/math_opt/elemental/elemental_to_string.cc
+++ b/ortools/math_opt/elemental/elemental_to_string.cc
@@ -120,7 +120,6 @@ std::vector<std::string> DiffDebugString(const Elemental& elemental,
     lines.push_back(absl::StrCat("  deleted: [",
                                  absl::StrJoin(deleted_elements, ", "), "]"));
   }
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   AllAttrs::ForEachAttr([&lines, &elemental, &diff]<typename Attr>(Attr attr) {
     if (diff.modified_keys(attr).empty()) {
       return;
diff --git a/ortools/math_opt/elemental/elements.h b/ortools/math_opt/elemental/elements.h
index d641bdd4652..82380a72a9d 100644
--- a/ortools/math_opt/elemental/elements.h
+++ b/ortools/math_opt/elemental/elements.h
@@ -18,11 +18,11 @@
 #ifndef ORTOOLS_MATH_OPT_ELEMENTAL_ELEMENTS_H_
 #define ORTOOLS_MATH_OPT_ELEMENTAL_ELEMENTS_H_
 
+#include <array>
 #include <ostream>
 #include <type_traits>
 
 #include "absl/strings/string_view.h"
-#include "ortools/base/array.h"
 #include "ortools/math_opt/elemental/tagged_id.h"
 
 namespace operations_research::math_opt {
@@ -34,7 +34,7 @@ enum class ElementType {
   kQuadraticConstraint,
   kIndicatorConstraint,
 };
-constexpr auto kElements = gtl::to_array(
+constexpr auto kElements = std::to_array(
     {ElementType::kVariable, ElementType::kLinearConstraint,
      ElementType::kAuxiliaryObjective, ElementType::kQuadraticConstraint,
      ElementType::kIndicatorConstraint});
diff --git a/ortools/math_opt/elemental/python/elemental.cc b/ortools/math_opt/elemental/python/elemental.cc
index d28ec4e117c..0e212d86647 100644
--- a/ortools/math_opt/elemental/python/elemental.cc
+++ b/ortools/math_opt/elemental/python/elemental.cc
@@ -365,7 +365,6 @@ R ApplyOnIndex(Fn fn, const int index) {
   CHECK_GE(index, 0);
   CHECK_LT(index, n);
   std::optional<R> result;
-  // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
   ForEachIndex<n>([index, &fn, &result]<int k>() {
     if (k == index) {
       result = fn.template operator()<k>();
@@ -384,7 +383,6 @@ absl::StatusOr<std::vector<AttrKeyFor<AttrType>>> DynamicSlice(
     const int element_id) {
   RETURN_IF_ERROR(ValidateSliceKeyIndex(attr, key_index));
   return ApplyOnIndex<GetAttrKeySize<AttrType>()>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&e, attr, element_id]<int k>() {
         return e.Slice<k, Elemental::StatusPolicy>(attr, element_id);
       },
@@ -401,7 +399,6 @@ absl::StatusOr<int64_t> DynamicGetSliceSize(const Elemental& e,
                                             const int element_id) {
   RETURN_IF_ERROR(ValidateSliceKeyIndex(attr, key_index));
   return ApplyOnIndex<GetAttrKeySize<AttrType>()>(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&e, attr, element_id]<int k>() {
         return e.GetSliceSize<k, Elemental::StatusPolicy>(attr, element_id);
       },
@@ -633,7 +630,6 @@ PYBIND11_MODULE(cpp_elemental, py_module) {
 
   // Export attribute operations.
   ForEach(
-      // NOLINTNEXTLINE(clang-diagnostic-pre-c++20-compat)
       [&elemental]<typename Descriptor>(const Descriptor&) {
         using AttrType = typename Descriptor::AttrType;
         using ValueType = typename Descriptor::ValueType;
diff --git a/ortools/routing/filter_committables.h b/ortools/routing/filter_committables.h
index da4d79ffb1f..3f591cb60d8 100644
--- a/ortools/routing/filter_committables.h
+++ b/ortools/routing/filter_committables.h
@@ -58,7 +58,7 @@ template <typename T>
 class CommittableArray {
  public:
   // Makes a vector with initial elements all committed to value.
-  CommittableArray<T>(size_t num_elements, const T& value)
+  CommittableArray(size_t num_elements, const T& value)
       : elements_(num_elements, {value, value}), changed_(num_elements) {}
 
   // Return the size of the vector.
diff --git a/ortools/sat/colab/README.md b/ortools/sat/colab/README.md
index 1a5dc85d724..f4de2f358c7 100644
--- a/ortools/sat/colab/README.md
+++ b/ortools/sat/colab/README.md
@@ -12,7 +12,7 @@ Below you'll find three examples of Google's CP-SAT solver.
 Build and run locally:
 
 ```
-bazel run -c opt --cxxopt=-std=c++17 ortools/python:ortools_notebook
+bazel run -c opt ortools/python:ortools_notebook
 ```
 
 This will open a jupyter notebook in your browser.
@@ -20,7 +20,7 @@ This will open a jupyter notebook in your browser.
 To use it as a server only, use the command
 
 ```
-bazel run -c opt --cxxopt=-std=c++17 ortools/python:ortools_notebook -- --no-browser
+bazel run -c opt ortools/python:ortools_notebook -- --no-browser
 ```
 
 And paste the resulting url in your favorite environment, like visual studio code.
diff --git a/ortools/third_party_solvers/xpress_environment.cc b/ortools/third_party_solvers/xpress_environment.cc
index 1885cb75967..8f8dd962d63 100644
--- a/ortools/third_party_solvers/xpress_environment.cc
+++ b/ortools/third_party_solvers/xpress_environment.cc
@@ -16,8 +16,7 @@
 #include "ortools/third_party_solvers/xpress_environment.h"
 
 #include <cstdlib>
-// NOLINTNEXTLINE(build/c++17)
-#include <filesystem>
+#include <filesystem>  //NOLINT
 #include <functional>
 #include <string>
 #include <vector>
@@ -28,7 +27,6 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_join.h"
 #include "absl/synchronization/mutex.h"
-#include "ortools/base/logging.h"
 #include "ortools/base/status_builder.h"
 #include "ortools/third_party_solvers/dynamic_library.h"